Mode converter for filling level radar

Abstract

A mode converter for a level radar includes an input line introducing a high-frequency signal into the mode converter; a helix structure into which a conductor of the input line projects and which includes a plurality of helical electrical conductors; and a waveguide which encloses the helix structure. The helix structure is configured to convert the high-frequency signal from the input line into an H01 mode in the waveguide.

The invention claimed is: 
     
       1. A mode converter for a level radar, comprising:
 an input line introducing a high-frequency signal into the mode converter; 
 a helix structure into which an internal conductor of a coaxial cable of the input line projects, the helix structure including a plurality of helical electrical conductors; and 
 a waveguide enclosing the helix structure; 
 wherein the helix structure is configured to convert the high-frequency signal from the input line into an H01 mode in the waveguide. 
 
     
     
       2. The mode converter according to  claim 1 , wherein the conductor projects into the helix structure by more than 10% of the length of the helix structure. 
     
     
       3. The mode converter according to  claim 1 , wherein the waveguide is formed by a housing of the level radar. 
     
     
       4. The mode converter according to  claims 1 , wherein the helix structure is carried by a dielectric body which is arranged in the waveguide and wherein the dielectric body carries the helix structure on the outside thereof. 
     
     
       5. A level radar, comprising:
 a mode converter according to  claim 1 . 
 
     
     
       6. The mode converter according to  claim 1 , further comprising:
 a dielectric body including a first cylindrical portion which is enclosed by the helix structure; and 
 a socket in the first cylindrical portion, the socket configured to receive the internal conductor of the coaxial cable. 
 
     
     
       7. The mode converter according to  claim 6 , further comprising:
 a second cylindrical portion having a greater diameter than a diameter of the first cylindrical portion, in which the first cylindrical portion including the helix structure is received. 
 
     
     
       8. The mode converter according to  claim 7 , further comprising:
 a conical portion situated between the first cylindrical portion and the second cylindrical portion. 
 
     
     
       9. The mode converter according to  claim 7 , further comprising:
 an emission cone connecting to the second cylindrical portion in such a way that a shoulder is formed on the second cylindrical portion. 
 
     
     
       10. A method for manufacturing a mode converter, comprising the steps of:
 providing a carrier body; 
 including an input line introducing a high-frequency signal into the mode converter; 
 applying a metallic helix structure to the carrier body by metallizing a plurality of helical strips on the outside of the carrier body using laser direct structuring of the carrier body, the metallic helix structure shaped and sized for an internal conductor of a coaxial cable of the input line to project into the metallic helix structure, the metallic helix structure including a plurality of helical electrical conductors; and 
 including a waveguide enclosing the metallic helix structure, 
 wherein the metallic helix structure is configured to convert the high-frequency signal from the input line into an H 01  mode in the waveguide. 
 
     
     
       11. The method according to  claim 10 , wherein the carrier body is made of a plastics material which is suitable for metallization by a laser direct structuring. 
     
     
       12. The method according to  claim 11 , wherein the entire converter body is made of the plastics material. 
     
     
       13. The method according to  claim 10 , further comprising the step of:
 attaching the carrier body to a further plastics material body in such a way that the carrier body forms a first portion of the converter body to which the helix structure is applied and the further plastics material body forms at least a second portion by which the converter body is configured to be fixed to a housing. 
 
     
     
       14. The method according to  claim 13 , wherein the carrier body is a solid cylinder in such a way that the converter body merely includes the plastics material of the carrier body in the first portion in the interior of the helix structure. 
     
     
       15. The method according to  claim 13 , wherein the carrier body is a hollow cylinder and the carrier body is attached to the further plastics material body by being slid onto the further plastics material body.